28 Proceedings of the Royal Physical Society. 



side by side on a white slab, in a good ligbt, to add the 

 caramel solution from a burette to the distilled water, until 

 that is found to equal in colour the water contained in the 

 other tube. The burette being graduated in grains, every 10 

 grains consumed will represent one degree of colour. The 

 intensity of the colour is ascertained by looking down through 

 the length of the column. 



This process I have found very efficacious, which fact, with 

 its extreme simplicity, will, I believe, recommend it to all 

 who, like myself, have occasion to examine numerous samples 

 of water. 



IV. Principal Walley exhibited a specimen of a membrano- 

 ossific cyst. This cyst, which was obtained from a mare 

 (having formed an obstruction to parturition, and being 

 attached by an elastic pedicle to the internal surface of the 

 uterus), he looked upon as an instance of a perverted ovum, 

 inasmuch as the mare did not become pregnant until she had 

 been allowed the horse for two successive seasons, the cyst 

 thus being the result of the first impregnation. 



V. Dr Egbert Brown exhibited specimens of ferruginous 

 sand from the shores of Lochfyne. The iron was magnetic, 

 and similar to the specimens shown last session by Dr James 

 Middleton, only much less rich in iron. Similar sands are 

 found in various portions of the world, including many spots 

 on the Scottish shores. Dr Middletpn's specimens were ob- 

 tained from Bogamy Point, at the entrance to Eothesay Bay, 

 where it forms a very considerable deposit. It also occurs 

 at Kilmichael in the Kyles of Bute, and there seems to be a 

 de]30sit of a similar kind at Ettrick Bay. An interesting 

 circumstance, probably connected with this deposit, is that 

 captains of small coasters in the neighbourhood say that they 

 have noticed a divergence of the compass near the point 

 where the principal deposit lies. The physical properties of 

 magnetic iron ore are that it is not only attracted by the 

 magnet, but possesses magnetic properties itself. In the case 

 of the deposits on the Scottish shores, it might be applied to 

 economic purposes. 



